Because the specific heat value of engine oil is low and it has no cooling effect inside the engine. The combustion of fuel in an engine generates heat energy. When the engine is working, the engine oil can bring heat back to the oil tank and then radiate it into the air to help the water tank cool the engine. What really plays a cooling role is the water outside the engine shell.

Good engine oil can bring the carbide and worn metal particles on engine parts back to the oil tank through circulation, and wash away the dirt produced on the working surface of the parts through the flow of lubricating oil. The engine oil forms a sealing ring between the piston ring and the piston to reduce gas leakage and prevent external pollutants from entering.

Extended data:

Engine oil action

Shock absorption and buffering: When the pressure at the engine cylinder mouth rises sharply, the load on the piston, piston plate, connecting rod and crankshaft bearing suddenly increases, which is lubricated through the bearing, so that the impact load it bears plays a buffering role.

Wear resistance: adding lubricant to the friction surface can reduce the friction coefficient, thus reducing the friction resistance, saving energy and reducing wear. Lubricants between friction surfaces can reduce friction losses caused by abrasive wear, surface fatigue and adhesive wear.

Rust prevention and corrosion prevention: Lubricating oil can be adsorbed on the surface of parts to prevent water, air, acidic substances and harmful gases from contacting with parts.